When surgery is performed and wound closure is completed, there is an unmet need for an adhesive or sealant material that will seal the wound site and prevent fluid leakage in, for example, a vessel anastomosis or lung resection. Generally, the key requirements of a tissue adhesive/sealant are:                (1) In use, the adhesive/sealant must mimic the mechanical performance of undamaged tissue;        (2) The adhesive/sealant should provide sufficient tack for “primary” fixation with the opportunity for manipulation and re-alignment prior to setting strongly;        (3) Any exothermic process involved in the curing of the adhesive/sealant should not damage the surrounding tissue;        (4) The adhesive/sealant must not elicit any toxic response by the surrounding healthy tissue and should facilitate the regrowth of new tissue where possible;        (5) The adhesive/sealant should not liberate harmful degradation products;        (6) The adhesive/sealant should degrade, and as it does so, it should be replaced by new tissue with minimal scarring; and        (7) Any biodegradation products should not accumulate in the body but should be eliminated naturally either by excretion or incorporation into the natural biochemical cycle.            [“Polymeric Biomaterials”, 2nd Ed., Marcel Dekker Inc., (2002) pp. 716]
Latent curing adhesives are well known in the field of industrial coatings, adhesives and sealants. For example, a latent curing adhesive may be the reaction product of a two-component mixture, one component being the reactive moiety, such as an epoxy or silicone resin, and the other component being the latent curing agent. More specifically, the latent curing agent may be present in the two component mixture in a non-reactive form, i.e., latent form, during manufacture, storage and non-use, but may then be converted to a reactive curing agent upon application and use. As an example, the latent curing agent may be converted to a reactive curing agent in the presence of moisture that is present in the environment or supplied to the site upon use. It is well known in the art, for example, that a ketimine moiety may be used as a latent curing agent that may be converted to a reactive curing agent, i.e., an amine moiety, in the presence water. After the ketimine moiety has been converted to its amine counterpart, the amine moiety may then react with the second component of the mixture, i.e., a reactive moiety such as an epoxy or silicone resin, to form the desired adhesive and/or sealant. Examples of various ketimines and latent curing adhesives are described in U.S. Pat. No. 6,525,159.
However, the latent curing adhesives described in the prior art are intended for industrial use, and are unsuitable for human use as an internal adhesive or sealant. Therefore, it is desirable to have a moisture-activated latent curing adhesive or sealant mixture that is capable of polymerizing in vivo to form an internal tissue adhesive or sealant. Additionally, it is desirable that such a moisture activated latent curing adhesive or sealant mixture be simple to use and handle, i.e., can be delivered as a single mixture, and is in the form of a flowable mixture that can be delivered to a surgical site, via for example, a syringe.